Alteration of gonadotropin-releasing hormone receptor expression with the progression of prostate cancer in the Dunning rat adenocarcinoma sublines.

Inhibitory effects of GnRH analogues on tumour growth in vitro suggests that such direct effects may be of importance also in vivo. However, the role of GnRH receptors (GnRH-R) in prostate tumour progression is largely unknown. The aim was therefore to investigate the variation of GnRH-R expression with prostate tumour progression using Dunning rat adenocarcinoma sublines representing different prostate tumour grades. GnRH-R levels were quantified in the rat dorsolateral (DLP) and Dunning sublines (PAP, AT-1, AT-2, AT-3, MatLyLu) using competitive RT-PCR and Western blot. The results showed that all Dunning sublines had significantly elevated GnRH-R mRNA expression levels compared with DLP. Comparison of GnRH-R mRNA levels between different tumour grades revealed no difference in mRNA expression. However, the anaplastic and highly metastatic AT-3 and MatLyLu tumours displayed a tendency for lower GnRH-R mRNA values than the non-metastatic tumour sublines. Our data demonstrate the expression of GnRH-R in normal rat DLP and in different Dunning sublines. However, GnRH-R seems not to be involved in tumour progression.